Peripheral Serial Interface (PSI5) is a standardized interface of the PSI5 organization and is based on a two-wire line and is used to connect peripheral sensors to electronic control units in automotive electronics. PSI5 uses two wires for both power supply to the sensors and data transmission. The controller provides a supply voltage and synchronization pulses modulated on this supply voltage. By selectively omitting synchronization pulses or varying the length thereof, a few bits can be transmitted from the controller to the sensor in order to set certain operation modes there, for example. The data is transmitted from the sensor to the controller by current modulation on the supply lines. In vehicles, in order to record vehicle state variables, for example in order to sense collisions, multiple sensors are connected to motor vehicle controllers, for example a central controller for passenger protection devices. One or more sensors are operated via a common communication bus (PSI5). For safety reasons, signals are always required from two independent sensors in order to activate restraint devices. If the data from two independent sensors is received by means of a single receiver, a single error in this receiver can result in an erroneous change of both sensor signals—and can therefore result in a safety-critical malfunction.
In particular, the reception unit is not checked during the normal operating cycle. U.S. 2009/0292961 A1, which is incorporated by reference, presents an integrated circuit including a plurality of transmitters and receivers, in which the output of one transmitter is connected directly to the receiver to be tested, in order to test the operation of a receiver. However, the precondition of this is that an identical signal is transmitted from the controller to the sensor as is transmitted from the sensor to the controller, which is not the case with the PSI5.